Fluid flow switch



Patented July 20, 1937 f FLovv svvrrcn' v John P. Ruth, New-York, N. Y.,' assignor to General Electric Vapor Lamp Company, Hoboken, 1

N. J., a corporationof New Jersey Application June 3, 1936, Serlal -No. 83,360 1.01m, (Cl. 200-452 The present invention relates to fluid flow switches. a p

A particular object of the invention is to provide a novel fluid flow switch which will maintain a circuit closed therethrough in all positions thereof except for a small angle in any direction from a given axis. Other objects and advantages of my invention will appear from the following detailed description or from an inspection of the accompanying drawing.

The invention consists inthe new and novel structure hereinafter set forth and claimed.

For various special applications it has been desired to produce a switch which will be open when within an angle of say 20 to 35 in any direction from a given axis, but which will be closed when in any other position. I have now discovered that this resultis accomplished by means of a novel mercury switch of my invention. According to my invention a mercury switch of the tubular or bulbous type is provided with a quantity of mercury which is sufficient to extend above the center of the switch envelope in any position of the switch. Either an inlead or a metal shell is then provided to make contact with this mercury at all positions of the switch, while a ring-shaped contact concentric with the axis of the envelope and arranged toward one end of said envelope provides the second contact with the mercury when the switch is in the closed circuit positions. By adjusting the height of this contact above the mercury level when the axis of the switch is vertical the switch is arranged to close the circuit as soon as the switch is tilted from this position in any direction to any desired angle. The ring contact is preferably made as large as convenient in order to make the operatlon of the switch certain at the desired angle.

In some cases, as where the switch is of especially small diameter, the action of the mercury tends to be slightly sluggish. I have found, however, that this tendency is overcome by introducing within the switch a small quantity ofrefractory' dust, such as that of silica or magnesia, which results in the lively response of the mercury to any movement of the switch. I have further found that undesired operation of the switch to either open or: close the circuit when the switch 1 is subjected to violent agitation is avoided by use of a suitable surge impeding baflle in the path of the mercury.

For the purpose of illustrating my invention I have shown two preferred'embodiments thereof in the accompanying drawing, in which Fig. l is -an elevational viewl of a mercury;

switchfshown in theopen circuit position,

' Fig.2 is 'a cross sectional view ofthe same I switch taken. on theline-fZ-Z of Fig.1, and

' Fig. 3 is asectional elevation of a modification of the switch of Fig. 1. i

As shown in the drawing, with particular refer-- ence to Figs. 1 and 2, my novel switch has a tubular envelope I closed at the lower end by-a pinch seal through which the inleads 2 and 3 are sealedin a conventional manner. vThe inleads! extends axially along the envelope l to a point a little 7 more than half way toward the. opposite end w thereof, while the inlead 3, which is enclosed within an insulating sheath 4 of glass or the like,

extends still nearer the opposite end of said 7 only slightly smaller diameter than saidenvelope.

is desired that the switch should close. A small amount of silica or other refractory dust not shown) is introduced into the envelope I, particularly when said envelope is of fairly small diamsurface of the mercury 6, rendering the latter responsive to very slight movements of the, envelope l. The inlead '2 and the ring contact 5 are of any.

suitable material, such as tungsten or a chrome iron alloy, but where an especially low resistance. is desired these elements are preferably formed with a platinum sheath which will bewetted by the mercury to form a low resistance contact. So 3- faras the inlead 2 is concerned, this sheath may envelope, where .itcarries the ring contact 5 of 'eter, of the order of 4. inch, where itfioatson the j be limited-to the tip thereof, which is'always in contact with the mercury 6, and may consist of a small piece of platinum welded'to said inlead, this construction having been found to produce excellent results. The envelope I preferably contains an atmosphere of hydrogen at any suitable pressure, and is sealed oil? at the tip in theusual manner." I

The switch shown in Fig. 3 is similar in con-- the envelope I I is made of a suitable metal such as a chrome iron alloy containing 26-30% chromium and 68-72 iron, and known asAllegheny 55. The lower end of said envelope is sealed with ,a disc I2 of a suitable glass, through which there extends an inlead 3'. Saidinlead, which has an .45 struction'toj that of Fig. 1, but in this iiistance insulating sheath 4 of glass or'the IikeQeXtends to a point well beyond the center of said envelope,

and at its end supports the ring contact 5 of I tungsten, platinum sheath wire or the like. The mercury 6 fills said envelope to a point'beyond the center of said envelope but below said contact. Hydrogen is also provided in this switch, as in Fig. 1. The envelope H is conveniently closed by, drawing in the end and welding. Where desired a baffle l3 of insulating material is supported on the sheath 4' at a point just below the ring contact 5 to protect said ring from splashing contact when the switch is violently agitated.

In the operation of either of these'switches when the switch is tiltedin anydirection from the position illustrated the mercury 6 flows to- I 'when the switch is the other end'u'p, due to the fact that 'the switch is more than half 'filled with mercury.

} While I have described my invention by reference to certain specific structures it is to be understood that it is not limited thereto, but that various changes omissions and substitutions, within the scope of the appended claim, may be made therein without departing from the spirit of the invention.

: Iclaim asmyinvention:-

A-fluid flow-switch comprising a sealed envelope whose volume is more than half filled with a conducting fluid, means to make contact with said-fluid at all positions of said switch, a ring contact coaxial with said envelope and disposed above the surface of said mercury in one position of said switch, whereby a limited tilting of said i switch in any direction closes the circuit through said switch, .said circuit remainingclosed when the position of said switch is completely reversed, and a baiile between said mercury and said ring contact in the open circuit position of said switch to prevent a splashing contact of said mercury with said ring. 1

" JOHN P. RUTH. 

